LAN ( Local Area Network, is the concept of internal computer network) is a network system used to connect computers in a small area such as offices, companies, houses.
LAN connects with other internal networks through subscriber lines, subscription services, through the Internet using VPN technology.
Another form of LAN is called WAN (Wide Area Network), used to connect LANs together (through router), WLAN (Wireless LAN) – wireless LAN is also a form of LAN using wireless device.
LAN can include server, signal connection devices (Repeater, Hub, Switch, Bridge), client, network interface card – NIC, and cable to connect computers together. With MS-DOS operating system, LAN servers often use Novell NetWare software, now developed technology, Windows NT and Windows for Workgroups appear have changed these concepts, LAN speed can be increased to 10 Mbps, 100 Mbps or even 1 Gbps.